title: Human skeletal muscle fibroblasts, but not myogenic cells, readily undergo adipogenic differentiation.
abstract: We characterised the adherent cell types isolated from human skeletal muscle by enzymatic digestion, and demonstrated that even at 72 hours after isolation these cultures consisted predominantly of myogenic cells (CD56(+), desmin(+)) and fibroblasts (TE-7(+), collagen VI(+), PDGFRα(+), vimentin(+), fibronectin(+)). To evaluate the behaviour of the cell types obtained, we optimised a double immuno-magnetic cell-sorting method for the separation of myogenic cells from fibroblasts. This procedure gave purities of >96% for myogenic (CD56(+), desmin(+)) cells. The CD56(-) fraction obtained from the first sort was highly enriched in TE-7(+) fibroblasts. Using quantitative analysis of immunofluorescent staining for lipid content, lineage markers and transcription factors, we tested if the purified cell populations could differentiate into adipocytes in response to treatment with either fatty acids or adipocyte-inducing medium. Both treatments caused the fibroblasts to differentiate into adipocytes, as shown by loss of intracellular TE-7, upregulation of the adipogenic transcription factors PPARγ and C/EBPα, and adoption of a lipid-laden adipocyte morphology. By contrast, myogenic cells did not undergo adipogenesis and showed differential regulation of PPARγ and C/EBPα in response to these adipogenic treatments. Our results show that human skeletal muscle fibroblasts are at least bipotent progenitors that can remain as extracellular-matrix-producing cells or differentiate into adipocytes.
authors.affiliation: Centre of Human and Aerospace Physiological Sciences, School of Biomedical Sciences, King's College London, Shepherd's House, Guy's Campus, London SE1 1UL, UK.
authors.forename: Chibeza C
authors.initials: CC
authors.lastname: Agley
authors.forename: Anthea M
authors.initials: AM
authors.lastname: Rowlerson
authors.forename: Cristiana P
authors.initials: CP
authors.lastname: Velloso
authors.forename: Norman R
authors.initials: NR
authors.lastname: Lazarus
authors.forename: Stephen D R
authors.initials: SD
authors.lastname: Harridge
mesh_terms: D050156:Adipogenesis; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019002:CD56 Antigen / Q000378:metabolism; D054338:Cell Transdifferentiation; D002478:Cells, Cultured; D005227:Fatty Acids / Q000502:physiology; D005434:Flow Cytometry; D005647:Fucosyltransferases / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D018189:Immunomagnetic Separation; D016256:Lewis X Antigen / Q000378:metabolism; D050356:Lipid Metabolism; D018482:Muscle, Skeletal / Q000166:cytology; D058628:Myofibroblasts / Q000502:physiology*; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D019002:CD56 Antigen; C515848:CEBPA protein, human; D005227:Fatty Acids; D016256:Lewis X Antigen; C522918:NCAM1 protein, human; D047495:PPAR gamma; C066693:FUT4 protein, human; D005647:Fucosyltransferases
keywords: Adipogenesis; Fibroblasts; Satellite cells; Skeletal muscle; Stem cells; Transdifferentiation